JP2013145686A - Vehicular battery stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery stack which shields a conduction path for electrically connecting adjacent unit cells or a unit cell and a reinforcing member, due to the generation of dew condensation water.SOLUTION: A battery stack has a laminated body, a pair of end plates 3, a reinforcing member 5 and a shielding member 6. The laminated body is made by alternately laminating a plurality of unit cells 21 and separators, and the pair of the end plates 3 is disposed at positions sandwiching the laminated body. The reinforcing member 5 is positioned on the opposite side to the laminated body across the end plate 3, and reinforces the stiffness of the end plate 3. The shielding member 6 is attached on an upper surface of at least any one of the unit cell 21, the separators, and the end plate 3. The wettability of a surface of the shielding member 6 is lower than the wettability of a surface of the unit cell 21, a surface of the separator, and a surface of the end plate 3 on which the shielding member 6 is attached.

Description

  The present invention relates to a technique for preventing energization through condensed water in a battery stack including a stacked body in which a plurality of single cells are arranged.

  As a battery stack for vehicles, a laminated body in which a plurality of single cells are laminated, an end plate disposed at a position sandwiching the laminated body, and the end plate is fixed to the vehicle body to reinforce the strength of the end plate. What has the reinforcing member to do is known.

  In this battery stack, a separator having a large number of through holes is located between adjacent unit cells in order to prevent a temperature rise associated with the output of the unit cells. By causing the air outside the vehicle compartment and outside the vehicle to flow into the through hole of the separator, it is possible to prevent the temperature of the unit cell from rising.

  However, since it is a structure that prevents the temperature of the unit cell from rising due to the air inside the vehicle interior or outside the vehicle, the air reaches the dew point due to the change in the relative humidity of the air and the environment in which the vehicle is driven, and the unit cell Condensation water is generated around the area. Specifically, dew condensation water is generated when a vehicle that has cooled down outdoors in a cold region enters a warm parking lot. This is because warm air outside the vehicle (parking lot) contacts the cell via the through hole of the separator and is cooled by the battery stack that has cooled down while left outdoors, and reaches the dew point temperature of the air. . When this dew condensation water is generated between adjacent unit cells and is bridged between the unit cells, if there is a potential difference between the bridged unit cells, a non-designed conduction path is formed.

  In addition, if condensed water accumulates on the upper surface of the end plate, an energization path through the condensed water may be formed between the unit cell and the reinforcing member, and a part of the current of the unit cell is Probability of flowing to the body arises. Furthermore, if the state where the dew condensation water adheres to the outer can of the unit cell, the outer can is corroded. If such a state where the outer can is corroded continues, a hole is formed in the outer can and leakage occurs. Therefore, in a battery stack for a vehicle, it is a very important problem to prevent the dew condensation from bridging between adjacent single cells or from bridging the single cells and the reinforcing member. is there.

  As a prior art, a method is disclosed in which the surface of the outer can of a plurality of single cells is coated with fluorine or silicon to provide a water repellent layer to prevent dew condensation from bridging between adjacent single cells (for example, Patent Document 1).

  In addition, there is disclosed a method in which a dew condensation waterproof sheet made of an insulating plastic sheet is attached to both side edges of an outer can of a plurality of unit cells to prevent dew condensation from bridging between adjacent unit cells ( For example, Patent Document 2).

JP 2010-170870 A

JP 2010-153141 A

  However, when the water repellent layer or the dew condensation waterproof sheet is provided on the outer peripheral surface of the unit cell as in Patent Documents 1 and 2, the side surface of the unit cell can use the weight of the dew condensation water that works downward. Can be dropped from the side of the unit cell, but the weight of the condensed water is not available on the upper surface of the unit cell, so the condensed water accumulates on the upper surface of the unit cell, and the condensed water is formed between adjacent unit cells. May bridge. Also, there is a possibility that condensed water accumulates on the upper surface of the end plate, and the accumulated condensed water energizes the unit cell on one side of the end plate and the reinforcing member adjacent to the other side of the end plate. There is.

  Therefore, the present invention shields the conduction path for energizing between adjacent cells or the conduction path for energizing the cell and the reinforcing member by the generation of condensed water so as not to form a conduction path due to condensed water. A battery stack is provided.

  In order to solve the above problems, the battery stack of the present invention includes a laminate, a pair of end plates, a reinforcing member, and a first member. The laminate is obtained by alternately laminating a plurality of single cells and separators, and the pair of end plates are arranged at positions sandwiching the laminate. The reinforcing member is located on the opposite side of the laminate with the end plate interposed therebetween, and reinforces the strength of the end plate. The first member is attached to the upper surface of at least one of the unit cell, the separator, and the end plate. Further, the wettability of the first member surface is lower than the wettability of the surface of the unit cell, the separator surface, and the end plate surface to which the first member is attached.

  In addition, the battery stack of the present invention is attached to a stacked body in which a plurality of unit cells and separators are alternately stacked, a pair of end plates disposed between the stacked body, and the pair of end plates, A restraining band that restrains the laminate, a reinforcing member that is attached to an end of the restraining band, is located on the opposite surface of the laminate with the end plate interposed therebetween, and reinforces the strength of the end plate; The unit cells adjacent to each other on the upper surface of the unit cell, which are attached to the upper surface of at least one of the cell, the separator, and the end plate, and are formed by condensed water adhering to the unit cell, the separator, and the end plate. There are few paths that conduct between each other or a path that conducts the cell and the reinforcing member on the upper surface of the end plate. A shielding member that shields at least one, wherein the wettability of the shielding member is lower than the wettability of the unit cell, the separator, and the end plate to which the shielding member is fixed. To do.

  According to the present invention, it is possible to prevent energization through the dew condensation water even in a situation where the dew condensation water is generated, and to supply electric power for driving the vehicle.

It is a perspective view of the battery stack for vehicles concerning a 1st embodiment of the present invention. It is AA sectional drawing of the battery stack shown in FIG. It is a detailed perspective view of the end plate in the battery stack of the first embodiment of the present invention. It is the schematic when condensed water generate | occur | produces on the upper surface of the end plate in the battery stack of 1st Embodiment of this invention. It is the schematic when condensed water generate | occur | produces on the upper surface of the end plate in the battery stack of 2nd Embodiment of this invention. It is the schematic when condensed water generate | occur | produces on the upper surface of the end plate in the battery stack of 3rd Embodiment of this invention.

(First embodiment)
Hereinafter, 1st Embodiment of the battery stack 1 of this invention is described. 1 is a perspective view of a battery stack 1 for a vehicle, FIG. 2 is a cross-sectional view of the battery stack 1 taken along line AA in FIG. 1, and FIG. 3 is a detailed perspective view of an end plate 3. The battery stack 1 of the present embodiment is fixed to the vehicle via a battery stack fixing member 9 that is coupled to the body of the vehicle (not shown).

  As shown in FIG. 1, the battery stack 1 of the present invention includes a stacked body 2 in which a plurality of single cells 21 and separators 22 are stacked alternately in the y-axis direction, and a pair of ends disposed at positions sandwiching the stacked body 2. And a restraint band 4 that is attached to the pair of end plates 3 and that is positioned on the opposite surface of the laminate 2 with the end plates 3 interposed therebetween and restrains the laminate 2. The battery stack 1 further includes a reinforcing member 5 that is attached to the end of the restraining band 4 and reinforces the strength of the end plate 3. Then, a path that is attached to the upper surface of the end plate 3 and that is formed by the unit cell 21, the separator 22, and the condensed water adhering to the end plate 3 connects the unit cell 21 and the reinforcing member 5 on the upper surface of the end plate 3. And a shielding member 6 (first member) for shielding.

  As shown in FIG. 1, the unit cell 21 has a plate shape extending in the x-axis direction, and includes a protruding positive electrode terminal 211 and negative electrode terminal 212 on the upper surface. The positive terminal 211 and the negative terminal 212 of such a unit cell 21 are electrically connected between adjacent unit cells 21 by a bus bar (not shown). As shown in FIG. 2, the separator 22 includes a plurality of through holes 221 formed in the contact surface (xz plane) with the unit cell 21 and extending in the x-axis direction. A certain distance is maintained so as not to contact. In this way, the unit cells 21 can be cooled by allowing the air outside the cell stack 1 to flow into the battery stack 1 through the through holes 221 while holding the adjacent unit cells 21 at a constant distance. Here, the unit cell 21 may be a lithium ion battery or a nickel metal hydride battery. The single battery 21 may be a battery cell or a battery module in which a plurality of battery cells are connected. Moreover, a battery cell means the element of the minimum unit which can be charged / discharged.

  As shown in FIG. 3, the end plate 3 is made of a plate-shaped resin material extending in the x-axis direction, and the end surface of the xz plane has the battery stack fixing member 9 and the reinforcing bracket shown in FIG. In order to fix 5 to the end plate 3, a first fixing groove 31 for screwing the first fixing bracket 7 and a second fixing bracket 8 to fix the restraining band 4 to the end plate 3. It has the 2nd fixing groove 32 which screws together (refer FIG. 2). On the upper surface of the end plate 3, a shielding member 6 that shields a conduction path through which condensed water conducts from the unit cell 21 to the reinforcing member 5 is located. The shielding member 6 is a plate-like member that is formed of a material having lower wettability (easiness to fit to the material surface by water droplets) than the surface of the end plate 3 and has a rectangular shape when viewed from the yz section. is there.

  As shown in FIG. 1, the restraint band 4 extends along the stacking direction (y-axis direction) of the unit cell 21 and the separator 22, and both end portions are bent downward. The end plate 3 can be fixed by the bent portion of the restraining band 4 to restrain the cell 21 and the separator 22.

  The reinforcing member 5 is made of, for example, a thin steel plate, and is located on the opposite side of the laminate 2 with the end plate 3 interposed therebetween. In order to stabilize the output of the unit cell 21, the end plate 3 holds the plurality of unit cells 21 and the separator 22 with a constant pressure by the restraining band 4. The reinforcing member 5 reinforces the strength of the end plate 3 so that pressure is applied to the laminate 2 even with the end plate 3 made of a resin material, and fixes the laminate 2 to the battery stack fixing member 9 which is a part of the vehicle. .

  FIG. 4 shows a schematic diagram when condensed water is generated on the upper surface of the end plate 3. In the battery stack 1 according to the present invention, the outside air of the battery stack 1 is cooled through the through-holes 221 of the separator 22, so that the dew condensation water 10 is changed to It occurs on the surfaces of the separator 22 and the end plate 3. For example, the dew condensation water 10 is likely to be generated when a vehicle that has cooled down outdoors in a cold district enters a warm parking lot. This is because warm air comes into contact with the unit cells 21 and the end plate 3 that have cooled down during standing outdoors through the through holes 221 of the separator 22 to reach the dew point temperature. This is because condensed water 10 is generated on the outer peripheral surface.

  When a large amount of the condensed water 10 is deposited on the upper surfaces of the unit cells 21, the separators 22, and the end plates 3, in the battery stack as in Patent Documents 1 and 2, the positive terminals 211 and the negative terminals 212 of the unit cells 21 are reinforced. A path (a bold arrow portion in FIG. 2) for energizing the working member 5 through the condensed water 10 is formed. When the conduction path is formed by the dew condensation water 10, the unit cell 21 and the outside of the battery stack 1 (vehicle body) are energized by the conduction path by the dew condensation water 10, the reinforcing member 5 and the battery stack fixing member 9. End up.

  Compared with Patent Documents 1 and 2, the battery stack 1 of the present invention has the shielding member 6 positioned on the upper surface of the battery stack 1, and thus the reinforcing member 5 from the unit cell 21 by the condensed water 10 as described above. It is possible to prevent a conduction path from being formed. This is because the dew condensation water 10 generated on the shielding member 6 is absorbed by the surface of the end plate 3 having higher wettability than the shielding member 6 as shown in FIG. Specifically, a material having low wettability such as the shielding member 6 is in a water-repellent state without allowing the condensed water to permeate the contact surface, and the condensed water 10 is added to the end plate 3 having higher wettability than the shielding member 6. (A material with low wettability has a large contact angle (an angle formed by the condensed water 10 and the contact surface), and a material with high wettability has a small contact angle). As described above, when the condensate water 10 is generated in a region where the condensed water 10 is difficult to permeate by providing the shielding member 6 on the surface of the end plate 3 so that the condensed water 10 is difficult to permeate, the generated condensed water 10 is generated. Can flow through the end plate 3 having high wettability. With this configuration, a region where the condensed water 10 does not exist can be formed on the upper surface of the end plate 3, so that a conduction path for the condensed water 10 that connects the unit cell 21 and the reinforcing member 5 is formed. It can prevent, and it can prevent that some electric power from the cell 21 is output to a vehicle via the member 5 for reinforcement. Further, since the condensed water 10 does not adhere to the shielding member 6, it is possible to prevent the surface of the shielding member 6 from being corroded by the condensed water 10.

  As in this example, the shielding member 6 may be provided at least on the upper surface of the end plate 3 and may not be provided on the side surface of the end plate 3. Since the upper surface of the end plate 3 is a horizontal surface and the condensed water 10 attached to the end plate 3 cannot be dropped using the weight of the condensed water 10, the condensed water 10 is easily deposited on the upper surface of the end plate 3. Therefore, a path for energizing the unit cell 21 and the reinforcing member 5 is easily formed. On the other hand, since the side surface of the end plate 3 is a vertical surface extending in the Z-axis direction, the condensed water adhering to the end plate 3 falls due to gravity, and the unit cell 21 and the reinforcing member 5 are energized. This is because no route is formed. That is, by providing the shielding member 6 only on the upper surface of the end plate 3 where the dew condensation water 10 is accumulated and the unit cell 21 and the reinforcing member 5 may be conducted, the unit cell 21 and the reinforcing member are provided. 5 can be prevented from being formed. With this configuration, it is possible to reduce the usage amount of the shielding member 6 necessary for manufacturing the battery stack 1 and to reduce the cost for manufacturing the battery stack 1. In addition, it is good also as a structure which fixes the shielding member 6 to both the upper surface and side surface of the end plate 3. FIG.

(Second Embodiment)
In the first embodiment described above, a member that has a quadrangular shape when viewed from the yz cross section is exemplified as the shielding member 6. However, the present invention is not particularly limited to this, and the upper surface is simple as shown in FIG. A member inclined toward the battery 21 may be used. Thus, by making the upper surface of the shielding member 6 into an inclined surface on which the unit cell 21 side is lowered, the unit cell 21 and the reinforcing member 5 due to the dew condensation water 10 are conducted as compared with the shielding member 6 of the first embodiment. Formation of a conduction path can be prevented. That is, by adopting the shape of the shielding member 6 of the second embodiment, characteristics due to low wettability of the shielding member 6 (characteristics in which the condensed water 10 becomes water repellent with respect to the contact surface) and the shielding member 6. Due to the characteristic of using the gravity of the dew condensation water 10 due to the inclined surface, the dew condensation water 10 generated on the upper surface of the shielding member easily falls to the unit cell 21 side. Thereby, the shielding member 6 of 2nd Embodiment can shield effectively the conduction | electrical_connection path | route which conducts the cell 21 and the reinforcement member 5 compared with the shielding member 6 of 1st Embodiment.

  In the above description, the inclined surface of the shielding member 6 has been described as an inclined surface in which the unit cell 21 side is lowered. However, the present invention is not limited to this, and the inclined surface in which the reinforcing member 5 side is lowered. Also good. Moreover, in 2nd Embodiment, although demonstrated as a member which becomes a triangle shape when visually recognized from a yz cross section, a shape is not limited to this, The upper surface of the shielding member 6 is the cell 21 side or the member 5 for reinforcement. What is necessary is just to have the shape which inclines in any one of the side.

(Third embodiment)
In each of the above embodiments, the shielding member 6 is simply fixed to the upper surface of the end plate 3. However, in the third embodiment, for example, as shown in FIG. 6, the shielding member 6 is placed on the upper surface of the end plate 3. It is good also as a structure which forms the water intake groove | channel 11 which takes in the dew condensation water 10 in the surface of the end plate 3 to which the shielding member 6 was fixed. By forming the water intake groove 11 on the upper surface of the end plate 3 in this way, the condensed water 10 generated on the shielding member 6 and the upper surface of the end plate 3 is taken in the water intake groove 11 and easily goes to the side surface of the end plate 3. Thereby, formation of the conduction | electrical_connection path | route by the dew condensation water 10 can be inhibited more, and it can prevent that a part of electric current which flows from the cell 21 flows outside via the dew condensation water 10. FIG. In FIG. 6, the shielding member 6 has a quadrangular shape when viewed from the yz section, but may have the shape described in the second embodiment.

  In the first embodiment, the second embodiment, and the third embodiment, the shielding member 6 is provided on the upper surface of the end plate 3 to prevent the formation of a path for energizing the unit cell 21 and the reinforcing member 5. Although described as a thing, it is not restricted to this in particular, By fixing the shielding member 6 to the upper surface of the unit cell 21, the conduction | electrical_connection path | route which conducts the unit cell 21 and the reinforcement member 5 by the condensed water 10 is shielded. It is good also as a structure. Moreover, it is good also as a structure which shields the conduction | electrical_connection path | route which conducts between the adjacent cell 21 by fixing the shielding member 6 to the upper surface of the cell 21. FIG. With this configuration, it is possible to prevent the positive electrode terminal 211 and the negative electrode terminal 212 between adjacent unit cells 21 from being energized by the condensed water 10. Moreover, it can also prevent that the surface of the shielding member 6 which fixed the cell 21 is corroded by the dew condensation water 10. FIG.

  Furthermore, instead of fixing the shielding member 6 to the upper surface of the unit cell 21, the shielding member 6 may be fixed to the upper surface of the separator 22 positioned between the adjacent unit cells 21. With this configuration, it is possible to prevent the formation of a path for energizing adjacent unit cells 21 due to the generation of the dew condensation water 10. Moreover, it is good also as a structure which fixes the shielding member 6 in the upper surface of the separator 22 located between the cell 21 and the end plate 3. FIG. With this configuration, it is possible to prevent a path for energizing the unit cell 21 and the reinforcing member 5 from being generated due to the generation of the dew condensation water 10.

DESCRIPTION OF SYMBOLS 1 Battery stack 2 Laminate body 21 Cell 211 Positive electrode terminal 212 Negative electrode terminal 22 Separator
221 Through-hole 3 End plate 31 1st fixing groove 32 2nd fixing groove 4 Restraint band 5 Reinforcing member 6 Shielding member 7 First fixing bracket 8 Second fixing bracket 9 Battery stack fixing member 10 Condensation water 11 Intake groove

Claims (1)

A laminate in which a plurality of single cells and separators are alternately laminated;
A pair of end plates disposed at positions sandwiching the laminate;
A reinforcing member for reinforcing the strength of the end plate, located on the opposite side of the laminated body across the end plate;
A first member attached to the upper surface of at least one of the unit cell, the separator, and the end plate;
The battery stack characterized in that the wettability of the surface of the first member is lower than the wettability of the surface of the unit cell to which the first member is attached, the surface of the separator, and the surface of the end plate.

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